Any of the BIG plumbing places like tradelink etc have heaps of pipe that you can use. Try and get the UV stabilised stuff. You can get it from 90mm to 150mm from memory. You need an end cap to suit for one end and a stormwater connector (female/female connector with a thread on one side so you can screw a cap on it).
Glue together with blue plumbers goop.
I made two up for our jayco and it was less than $120 for 150mm pipe and fittings. Buy a full 6m length and you will save $$ over short pieces from a hardware place. Give the offcut to a mate or hit the kids with it. Makes a good thump sound
![Smiley :)](http://www.myswag.org/Smileys/classic/smiley.gif)
Here is a pic of my last one. This is the side with the fixed cap on it. It also has the fittings that builders use to hold the pipe onto a wall or trus;
![](http://i452.photobucket.com/albums/qq249/dazzler1966/AWDCamperTrailerforupload-39.jpg)